When you set out to cut a miter joint, the key to ending up with a perfect 90 degree joint isn’t so much in cutting two precise 45 degree angles. It has more to do with cutting two angles that add up to 90 degrees - precisely. And that’s what makes Rockler’s new 45 Degree Miter Sled such a handy thing to have around. This simple table saw sled makes it virtually impossible to cut a miter joint that fits together at anything other than a perfect 90 degrees.
How? Simple geometry. The sled consists of a one piece fence that forms an accurate 90 degree angle. This main component is positioned so that each of its clamping faces are at a 45 degree angle to a guide bar that fits in a standard ¾’’ x 3/8’’ miter slot. Cutting one part of a joint using the forward fence face, and the other using the rear virtually guarantees that the resulting joint will form a 90 degrees angle. Put in the form of an example: If one cut happens to be a smidgeon off – say, cut at 45.001 degrees – the next will be cut automagically at exactly 44.999 degrees. And voila – a perfect 90 degree miter joint is born.
Of course, this perfect correspondence of cut angles will only happen if the sled passes the blade at exactly the same angle each time. That’s been taken into account. The sled’s guide bar is equipped with adjustable nylon pins that ensure a snug fit in the miter slot and precise repeatability of the cut angle.
The through-slots in the guide’s base are another useful touch. They’re there so that you can get a clamp jaw all the way down flush with the surface of the table, on the inside of the sled. And it’s all made of tough polycarbonate plastic, so the fence will hold its shape and withstand an occasional fall to the floor, but will still permit easy drilling for attachment of a sacrificial sub-fence - in case you want to set up stop blocks for repeat cuts and to limit tear-out on the back side of the cut.
Some might question the wisdom of investing in a tool with such a limited range. After all, the 45 Degree Miter Sled only does one thing. But it’s an important thing. When you think about it, cutting a 90 degree miter is just about the most popular operation in woodworking. What’s it worth to you to be able to do just that on a table saw, perfectly, every time – without having to mess with setting your miter gauge? Around $20, perhaps?